Plating with sulfides, selenides, and tellurides of chromium, molybdenum, and tungsten



March 9, 1954 J LANDER 2,671,739

PLATING WITH SULFIDES, SEILENIDES, AND TELLURIDES OF CHROMIUM, MOLYBDENUM', AND TUNGSTEN Original Filed Aug. 3, 1944 v To VACUUM PUMP 40 V Hora-Ass;

IN VEN T 0/? J. .4 LANDER ATTORNEY Patented Mar. 9, 1954 PLATING WITH SULFIDES, SELENIDES, AND

TELLURIDES OF CHROMIUM,

MoLYB- DENUM, AND TUNGSTEN James J. Lander, Millington, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Continuation of abandoned application Serial No. 547,910, August 3,1944. This application June 22, 1949, Serial N 0. 100,728

Claims. (Cl. 117-106) This invention relates to processes for coating objects with sulphides, selenides and tellurides of one of the metals chromium, molybdenum or tungsten or with mixtures of such substances.

This application is a continuation of my application Serial No. 547,910, filed August 3, 1944, and now abandoned, and all benefits legally flowing from its copendency therewith are claimed.

The invention relates, more particularly, to coating solid metals or metallic alloys with tightly adhering coatings of such substances but the invention is not restricted to coating metals and may be employed for coating other objects of a nature which may be brought to a proper high temperature condition necessary to apply the coating.

Objects may be coated for various purposes, for example ornamentation, to render them weather resistant, to render their surfaces non-conducting or, in some instances, to make them photoelectric. Pointed or other objects may be coated to give them rectifying properties. Thinmagnetic sheet material may be coated for the purpose of producing thereon an electrically resistant layer which may be uniform and thin, for example, from 0.001 to 0.0001 inch in thickness.

In a general way, plating may be accomplished by first removing impurities or other substances from the surface to be coated, especially those impurities or substances which would tend to prevent the production of a tightly adherent coatmg.

It may be desirable to coat the object to be plated first With a thin layer of metallic chromium, molybdenum and tungsten and then continue the plating with an oxide, sulphide, selenide or telluride. In general, the process is carried out by placing the object to be plated in avessel in which a low gas pressure may be obtained and introducing a carbonyl of the metal chromium, molybdenum or tungsten along with some gas which will supply the proper amount of oxygen, sulphur, selenium or tellurium and maintaining the object to be plated at a suitably high temperature which will vary under difierent conditions and with different substances but, in general, may range from 200 C. in certain cases up to 800 C. or even higher in other cases.

-Among the features of the invention are adaptability of the invention to the plating of inaccessible surfaces, depressions or grooves of objects; the removal of foreign bodies from the surface to be plated in order to promote the reproduction of a tightly adherent plate; the process of beginning plating with a metal or substantially pure metal covering it with one of the various metallic compounds of an adherent layer; maintaining a low pressure in the plating chamber; utilization of proper temperatures in combination with suitable gas pressures to produce the desired plating, and other features which will appear hereinafter.

For illustration of apparatus useful in carrying out the invention, reference is made to the accompanying drawings.

Fig. 1 is a diagram partly in cross-section of apparatus capable of being used for the purposes of the invention for plating a metallic sheet, for example, a thin sheet of magnetic material; and

Fig. 2 is a cross-sectional diagram of an arrangement for plating a surface of glass or similar vitreous material of any kind which can be raised to a sufiiciently high temperature to be plated.

Not only flat surfaces but concave, convex or surfaces of any other shape may be plated by utilizing properly modified apparatus.

Referring now to Fig. 1 and mode of operating it to plate an object, there is provided a ceramic or glass vessel H] which possesses a cooling water jacket ll having a water inlet 12 leading to a suitable source of water supply and a water outlet [3. The inlet and the outlet may be located at any suitable portion or portions of the glass or ceramic vessel 0. The vessel as illustrated is tubular in form and is provided with a large tightly fitting stopper l4 which may be made gas-tight by means of ground glass surfaces or otherwise and has connected to it two other tubes l5 and 16 which are U-shaped. Tube I5 is provided with valves l1 and Ila and a side inlet tube l'lb with a valve l'lc. Tube I6 is provided with a valve l8. A winding or coil 23 adapted to be traversed by'high frequency current supplied from suitable high frequency source I9 is hung, mounted or otherwise disposed about the central portion of the tube I0. An object 20 consisting of metal to be plated is represented as a thin sheet of magnetic material, for example, a ferromagnetic alloy consisting of 78 /2 per cent nickel and 22 /2 per cent iron. The object 20 typifies any one or more objects to be placed in the vessel [0 to be coated and is mounted on wedge-shaped supports of glass mica or ceramic material or is otherwise hung, supported or disposed within the vessel It]. In some instances it may be merely sufiicient to lay the ob ject 20.0r a group of objects 20 within the. vessel ID. The object 20 may consist of any type Of metal or metallic alloy which can be raised to the desired plating temperature hereinafter specified without becoming too soft or melting. In the operation of the device tube i6 is connected to a vacuum pump through a valve it, which may be.ofiany:c0nveniexit type, and the U tube-part "of the tube [6 maybe chilled in a vessel 25 containing a cooling fluid to entrap and thereby save undecomposed carbonyl. Tube ITb may be utilized to supply suitableggas suchzas oxygen, hydrogen sulphide, sulphnrivaporghydrogen selenide, or hydrogen telluride. These gases*may be oxygen, sulphur, selenium, tellurium, their hydrides and mixtures thereof. Metallic .carboniyls may be introduced directly through atube .15 through the series of valves l1 and Ila or alternatively the metallic carbonyl may be =plaeed in the U tube in solid form and-vaporized by'immersing the U tube [5 in a vessel 24 with a heated fluid. The vaporized metallic carbonyl .may be carried into the plating vessel by conducting a stream.of-.gas through the U tube] 5.

iEor utilizing the equipment of Fig. 2 Ito .plate ..0ne suffa 1eof a ceramic sheet 25 -.-the .sheet ,llaceil .adjacerit .to a structure which includes a .water lcooledjjacketfzfisuppliedwhh cold water -.Iromfililet.2 .leadi lg to. an loutletilt. The tube ""29 is provided with suitable ,valvesjleadingito a vacuum pump. andthe tubes 23.0.;and T3! also are gm'ovide'd with suitable valves serving .to supply "metallic carbonyl and suchgases. 2.5.318 MSG (Tin .accordance .withtheexamples setiorth or .eguiv- ;alent .or .similar examples. "Th .ca'rbonylgas along with other ,gases .supplie'dpass through a spacem whichisikept. conlby the water jacket and into a jpefforatedihead' 33 whichlhas a numfber ',of small'meriora'tions'i34 Zior Supplying the .rarbonyl vapor and .othergasesfto'the. surface of 7the'p1ate15. The-plate .25 is Ifirmly securedby "means of screws 40 'and-a "heat resistant gasket 4| which may be composed of a substancesuch as. copper. The'fianges'flar 'integral with or -otherwise secured in agas-tig'ht manner to a heating chamber #3 into which not gases'may be supplied from a furnace .toheat the plate "25 by heat conduction'to a desired"platingtemperature saswill'hereinafter bespecified.

The following :examples 'will be considered to "all ly egually'well .to the arrangement of "Fig. 1 for plating a metallic-sheet or toFig. 2 templating ones'ide of'avitreous Sheet as wellnstoiplat- 'ing other objects with suitable modifications of the equipment.

.Example 1 xberplated dstraised to a'temperaturemf 200 up to ..600 :or 800 '0. --by .high frequency induction \or otherwise. .-In addition .to metalliccarbonyLox- :ygen [is introduced -in -.-approximately istoichioemetric proportions, that is, oxygen and chr0- umium the proportions represented by the-formulaflrzoa. If the temperature is 110w, around 200 .C.,.an excess of nxygen,..CQz,.orHzOshould be introduced, but at higher temperatures \of around 400 TC. and upward, the excessof oxygen ;slrould"be reduced to :no excess .or a very slight excess. Plating or coating objects at the lower part of the range of temperatures allows a more rapid plating rate in that less decomposition in the gas phase will takeplace. Itis to. be understocdithat the .objectato besplated iszrendered free of foreign substances, One method of accomplishing this would be to treat the metal with acid and wash off the adherent acid with a sub- Sta-K885811011 :as alcohol immediately befor plac- 'ing :the .cbjecti-in the plating vessel and immehiately subjecting the object to applied vacuum lafterit hasbeen introduced into the plating vessel. "Thisremoves the residual alcohol by evaporation. Another way of cleaning the surface of the object to be plated is to introduce it into the plating=vessel=and=heating it by electromagnetic induction-to atemperature such as 600 C., while maintaining 'a how of H2 or other suitable gas :the ;plating chamber. This is done before introducing any carbonyl gas or other gases which are to be usedinplatingcperation.

Elia-ample 2 Compounds of chromium with selenium, such as Cr-Se and Crises,maybe'platedby introducing hydrogen selenide'H'zSe together with chro- -mium "carbonyl =in stoichiometric ratios 'appropriate'tozplate the desired compounds. uprating temperature around'400"C. to600 Crand'a pressure of l millimeter of mercury 'mayfbe employed.

Example 4 .Compounds :of tellurium and 'chromium, .such as CrTe and Cr'Iez maybeplated byiintroducing chromium carbonyl .and hydrogen .telluride :in stoichiometric ratios of .chromium and-tellurium suitable .to produce the desired compound. lllhe object to be plated may be heated to between 400 ,C. and 500 C. an-da .pressure of .-1 millimeter of .mercury maintained in :the plating chamber.

Example .5

Molybdenum oxides, such as purple molyb- :denum ioxides M0203, brownish purple molybdenum oxide 3MO3O8 and 'a white molybdenum 'oxide'MoO3 or mixtures thereof maybe "plated. Along with=the molybdenum carbonyl there may :be introduced air, pure oxygen, CO2, 'or'Hzb. Stoichiometric "amounts -of the gases introduced withtrespect to' themolybdenumandoxygen con- :tent may be-employed if high plating tempera- *turesrabove iOO C. are used. Atlowertemper- .atures an eXcessof oxidizing agent will be mecessary to counteractthe reducing tendency'of the carbon monoxide a tendency which is dependent upon ithe pressure. Gas pressures in the plating chamber :of :1 millimeter of mercury-or less may .beemployed.

V Example "6 1f molybdenum, such as MozS,mS

- and Moss may be plated by introducing molybdenum carbonyl along with hydrogen sulphide or sulphur "vapor in a manner analogous to the preparation of the oxides when introducing H2O. Plating temperatures of 400 C. or somewhat -5 higher and gas pressures in the plating chamber of 1 millimeter of mercury or less may be employed.

Example 7 selenides of molybdenum, such as MoSe2 and Mozses, or mixtures thereof may be plated. Along with the molybdenum carbonyl; hydrogen selenide HzSe may be introduced and a plating temperature of 400 C. to 600 C. and a pres- 57 sure of l millimeter of mercury or less may be employed.

Example 8 Example 9 Tungsten oxide, such as W205 which has a bluish-violet color, W02 which has a brownish color, and W0: which has a light yellow color, may be plated by introducing water, oxygen or CO2. Stoichiometric ratios with respect to the tungsten and oxygen of tungsten carbonyl and the oxygen containing gas may be employed, except at relatively low temperatures, in which case an excess of oxygen containing material should be employed. Plating temperatures of the surface to be plated may range from 400 C. to 800 C., and pressures of 1 millimeter of mercury or less should be mounted in the plating chamber.

Example 10 Tungsten sulphide, such as W812 and WSs, or mixtures thereof, may be plated by introducing tungsten carbonyl and hydrogen sulphide in suitable ratios with plating temperatures of 400 C. or somewhat higher and gas pressures of 1 millimeter of mercury or less.

Example 11 Tungsten selenide, such as WSez and WSez, may be plated by introducing tungsten carbonyl along with hydrogen selenide in suitable stoichiometric ratios of tungsten and selenium for the particular compound-desired with plating temperatures of 400 C. or upward and gas pressures in the chamber of l millimeter of mercury or lower.

Example 12 Tungsten tellurides, such as WTe and Wei, may be plated by introducing tungsten carbonyl and hydrogen telluride HzTe under conditions similar to those set forth with respect to the selenides of Example 11.

In every case set forth above, the plating operation may begin by introducing the metallic carbonyl alone or more preferably with an excess of hydrogen. A thin metallic plate of the metal chromium, molybdenum or tungsten may thus be deposited, which layer may be, if desired, very thin, perhaps no more than a thickness corresponding to a few molecules of the metal. Then by introducing the other gas, such :asthe oxygen,'sulphurgas, hydrogen sulphide, selenium gas, hydrogen selenide, tellurium gas, -or hydrogen telluride, the desired compound may be plated over the metal. This will promote adherence because it has already been dis- -closed by me that tightly adhering platings of such metals may be produced under suitable conditions if the surface of the base metal to be .plated is chemically free from impurities, such as-oxidesor other substances which would tend to impair the adhesion.

In plating or coating according to the present specification the highest permissible temperature of the surface. to be plated would ordinarily not exceed 800 C. but may be somewhat less or somewhat more dependent upon the particular substances which are used in plating and the particular compositions to be deposited. In every case the maximum temperature must be well 0 below the softening or decomposition point of the object to be .plated and also below the melting or vaporization point of the substance to be deposited as a plating or coating. Consequently, each and every one of applicant's claims is to be .construed, regardless of the specific language used therein, as having an upper temperature limit conforming to each and every one of the foregoing conditions.

What is claimed is:

1. The method of plating a surface of an object, which will withstand heating, which comprises maintaining the surface to be plated at a temperature in the range of from 200 to 800 0., continuously bringing in contact with the surface to be coated the gaseous carbonyl of an element selected from the group consisting of molybdenum, tungsten and chromium together with at least one gaseous substance selected from the group consisting of sulphur, selenium, tellurium and their hydrides, continuously withdrawing therefrom decomposition products and maintaining the total gas pressure at up to 5 millimeters of mercury.

2. The method of plating a surface of an object, which will withstand heating. which comprises maintaining the surface to be plated at a temperature in the range of from 400 to 800 0., continuously bringing in contact with the surface to be coated the gaseous carbonyl of an element selected from the group consisting of molybdenum, tungsten and chromium together with at least one gaseous substance selected from the group consisting of sulphur, selenium, tellurium and their hydrides, continuously withdrawing therefrom decomposition products and maintaining the total gas pressure at up to 5 millimeters of mercury.

3. The method of plating a surface of an object, which will withstand heating, which comprises maintaining the surface to be plated at a temperature in the range of from 400 to 800 C., continuously bringing in contact with the surface to be coated the gaseous carbonyl of an element selected from the group consisting of molybdenum, tungsten and chromium together with gaseous hydrogen sulphide, continuously withdrawing therefrom decomposition products and maintaining the total gas pressure at up to 5 millimeters of mercury.

4. The method of plating a surface of an object, which will withstand heating, with a molybdenum sulphide, which comprises maintaining the surface to be plated at a temperature in the range of from 400 to 800 0., continuously bringing in contact with the surface to-be coated th carbonyl or molybdenum. toge her with gaseous hydrogen sulphide. continuously withdraw n therefrom decomposition products maintaining the total as pressure at up to millimeters of mercury,

5. The method of plating a surface of an objeet, which will withstand heating, with a molybdenum sulphide, which comprises maintaining the sunfaee to-be plated in a, hermetically sealed enclosure. at a temperature in the range of from 400 to 800 C., continuously bringing in contact with the surface to be coated gaseous molybdenum carbonyl, together with gaseous hydrogen sulphide. continuously withdrawing therefrom decomposition produots and maintaining the toon a pretense at up to 5 mil imet n 91 mer- References Cited in thefile of this P34 09 STATES PATENTS 

1. THE METHOD OF PLATING A SURFACE OF AN OBJECT, WHICH WILL WITHSTAND HEATING, WHICH COMPRISES MAINTAINING THE SURFACE TO THE PLATED AT A TEMPERATURE IN THE RANGE OF FROM 200* TO 800* C., CONTINUOUSLY BRINGING IN CONTACT WITH THE SURFACE TO BE COATED THE GASEOUS CARBONYL OF AN ELEMENT SELECTED FROM THE GROUP CONSISTING OF MOLYBODENUM, TUNGSTEN AND CHROMIUM TOGETHER WITH AT LEAST ONE GASEOUS SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF SULPHUR, SELENIUM, TELLURIUM AND THEIR HYDRIDES, CONTINUOUSLY WITHDRAWING 